<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title></title>

	<style>
		nav {
			margin: 0 auto;
			font-size: 0;
			text-align: center;
			column-count: 2;
			column-width: 400px;
			column-gap: 9px;
			column-rule:  1px solid #333;
		}
		nav a {
			font-size: 14px;
			line-height: 2em;
			display: block;
			color: #fff;
			text-transform: uppercase;
			background-color: #333;
		}
	</style>
</head>
<body>
	<nav>
		<a href="">home</a>
		<a href="">github</a>
		<a href="">iserver</a>
		<a href="">workman</a>
	</nav>

	<ul>
		<li>不要给 a 添加高度,高度让内容添加,防止页面错乱</li>
	</ul>
</body>
</html>